Inverted pendulum type vehicle

ABSTRACT

An inverted pendulum type vehicle includes a first control processor that adds up a basic velocity command in a longitudinal direction and a lateral direction based on an operation through a joystick and a desired center of gravity velocity addition amount in the longitudinal direction and the lateral direction based on the movement of the body weight of the rider, thereby determining a desired velocity. A longitudinal travel velocity command limiter sets a desired center of gravity velocity addition amount, which is based on the basic velocity command based on a longitudinal manipulated variable of the joystick and a center of gravity offset influence amount based on the movement of the body weight of the rider, to a smaller value as a basic turn angular velocity command value increases.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an inverted pendulum type vehiclecapable of traveling on a floor surface.

2. Description of the Related Art

There has conventionally been known an inverted pendulum type vehicle inwhich a rider mounting section tiltable relative to the verticaldirection is attached to a base body, to which a travel operation unitthat travels on a floor surface and an actuator that drives the traveloperation unit are installed (refer to, for example, Japanese PatentApplication Laid-Open No. 2011-068165).

A rider of the inverted pendulum type vehicle moves the vehicle bymoving his/her weight or by operating an operation unit, such as ajoystick. It requires, however, a certain level of skill to move theinverted pendulum type vehicle exactly as the rider intends. Hence, ithas been difficult for a beginner, who is not experienced with theoperation, to operate the inverted pendulum type vehicle as he or sheintends.

SUMMARY OF THE INVENTION

The present invention has been made with a view toward overcoming theaforesaid shortcoming, and an object thereof is to provide an invertedpendulum type vehicle which permits an easier traveling operation for arider.

To this end, an inverted pendulum type vehicle in accordance with thepresent invention has:

a first travel operation unit capable of traveling on a floor surface;

a first actuator that drives the first travel operation unit;

a base body to which the first travel operation unit and the firstactuator are installed; and

a rider mounting section attached to the base body such that the ridermounting section is tiltable relative to a vertical direction,

wherein the first travel operation unit is configured to be capable oftraveling in all directions, including a longitudinal direction and alateral direction relative to a rider on the rider mounting section, bya driving force of the first actuator.

Further, the inverted pendulum type according to a first aspect of theinvention vehicle includes:

a second travel operation unit, which is connected to the first traveloperation unit or the base body with an interval provided from the firsttravel operation unit in the longitudinal direction and which isconfigured to be capable of traveling in all directions on a floorsurface;

a second actuator which generates a driving force for causing the secondtravel operation unit to travel at least in the lateral direction;

an operation unit which receives, from a rider on the rider mountingsection, a longitudinal travel operation instruction for a travel of theinverted pendulum type vehicle in the longitudinal direction, a lateraltravel operation instruction for a travel of the inverted pendulum typevehicle in the lateral direction, and a turn operation instruction formaking a turn of the inverted pendulum type vehicle;

a velocity command output unit which outputs a longitudinal travelvelocity command for causing the inverted pendulum type vehicle totravel in the longitudinal direction at a command velocity based on amanipulated variable of the longitudinal travel operation, a lateraltravel velocity command for causing the inverted pendulum type vehicleto travel in the lateral direction at a command velocity based on amanipulated variable of the lateral travel operation, and a turnvelocity command for causing the inverted pendulum type vehicle to turnat a command velocity based on a manipulated variable of the turnoperation;

a control processing unit which controls the traveling operations of thefirst travel operation unit and the second travel operation unit byoperating the first actuator and the second actuator according to thelongitudinal travel velocity command, the lateral travel velocitycommand, and the turn velocity command; and

a longitudinal travel velocity command limiting unit which sets thelongitudinal travel velocity command based on the longitudinal traveloperation to be lower as the manipulated variable of the turn operationincreases while the turn operation and the longitudinal travel operationare being performed through the operation unit.

In the inverted pendulum type vehicle according to the first aspect ofthe invention, if the manipulated variable of the turn operationincreases while the rider on the rider mounting section is performingthe turn operation and the longitudinal travel operation through theoperation unit, then it is assumed that the rider is trying to furtherturn the inverted pendulum type vehicle.

Hence, the longitudinal travel velocity command limiting unit sets thelongitudinal travel velocity command based on the longitudinal traveloperation to be lower as the manipulated variable of the turn operationincreases thereby to ensure an easier turn of the inverted pendulum typevehicle, enabling the rider to easily operate the inverted pendulum typevehicle.

Further, the inverted pendulum type vehicle according to the secondaspect includes:

a second travel operation unit, which is connected to the first traveloperation unit or the base body with an interval provided from the firsttravel operation unit in the longitudinal direction and which isconfigured to be capable of traveling in all directions on a floorsurface;

a second actuator which generates a driving force for causing the secondtravel operation unit to travel at least in the lateral direction;

an operation unit which receives, from a rider on the rider mountingsection, a longitudinal travel operation instruction for a travel of theinverted pendulum type vehicle in the longitudinal direction, a lateraltravel operation instruction for a travel of the inverted pendulum typevehicle in the lateral direction, and a turn operation instruction formaking a turn of the inverted pendulum type vehicle;

a velocity command output unit which outputs a longitudinal travelvelocity command for causing the inverted pendulum type vehicle totravel in the longitudinal direction at a command velocity based on amanipulated variable of the longitudinal travel operation, a lateraltravel velocity command for causing the inverted pendulum type vehicleto travel in the lateral direction at a command velocity based on amanipulated variable of the lateral travel operation, and a turnvelocity command for causing the inverted pendulum type vehicle to turnat a command velocity based on a manipulated variable of the turnoperation;

a control processing unit which controls the traveling operations of thefirst travel operation unit and the second travel operation unit byoperating the first actuator and the second actuator according to thelongitudinal travel velocity command, the lateral travel velocitycommand, and the turn velocity command; and

a turn velocity command limiting unit which sets the turn velocitycommand based on the turn operation to be lower as the manipulatedvariable of the longitudinal travel operation decreases while the turnoperation and the longitudinal travel operation are being performedthrough the operation unit.

In the inverted pendulum type vehicle according to the second aspect ofthe invention, if the manipulated variable of the longitudinal traveloperation decreases while the rider on the rider mounting section isperforming the turn operation and the longitudinal travel operationthrough the operation unit, then it is assumed that the rider is tryingto move the inverted pendulum type vehicle at a low speed.

Hence, the turn velocity command limiting unit sets the turn velocitycommand based on the turn operation to be lower as the manipulatedvariable of the longitudinal travel operation decreases. This makes itpossible to restrain the inverted pendulum type vehicle from turning ata high speed against the intention of the rider when the rider is tryingto move the inverted pendulum type vehicle at a low speed, thuspermitting easier operation of the inverted pendulum type vehicle forthe rider.

Further, an inverted pendulum type vehicle according to a third aspectof the invention includes:

a second travel operation unit, which is connected to the first traveloperation unit or the base body with an interval provided from the firsttravel operation unit in the longitudinal direction and which isconfigured to be capable of traveling in all directions on a floorsurface;

a second actuator which generates a driving force for causing the secondtravel operation unit to travel at least in the lateral direction;

an operation unit which receives, from a rider on the rider mountingsection, a longitudinal travel operation instruction for a travel of theinverted pendulum type vehicle in the longitudinal direction, a lateraltravel operation instruction for a travel of the inverted pendulum typevehicle in the lateral direction, and a turn operation instruction formaking a turn of the inverted pendulum type vehicle;

a velocity command output unit which outputs a longitudinal travelvelocity command for causing the inverted pendulum type vehicle totravel in the longitudinal direction at a command velocity based on amanipulated variable of the longitudinal travel operation, a lateraltravel velocity command for causing the inverted pendulum type vehicleto travel in the lateral direction at a command velocity based on amanipulated variable of the lateral travel operation, and a turnvelocity command for causing the inverted pendulum type vehicle to turnat a command velocity based on a manipulated variable of the turnoperation;

a control processing unit which controls the traveling operations of thefirst travel operation unit and the second travel operation unit byoperating the first actuator and the second actuator according to thelongitudinal travel velocity command, the lateral travel velocitycommand, and the turn velocity command; and

a turn velocity command limiting unit which sets the turn velocitycommand based on the turn operation to be lower as the manipulatedvariable of the lateral travel operation increases while the turnoperation and the lateral travel operation are being performed throughthe operation unit.

In the inverted pendulum type vehicle according to the third aspect ofthe invention, the control processing unit may cause the first traveloperation unit and the second travel operation unit to travel at thesame velocity in the lateral direction in order to cause the invertedpendulum type vehicle to travel in the lateral direction. Alternatively,the control processing unit may cause the first travel operation unitand the second travel operation unit to travel at different velocitiesin the lateral direction in order to cause the inverted pendulum typevehicle to turn. Hence, the travel velocity of the second traveloperation unit is determined on the basis of a resultant velocity of thedesired turn velocity and the desired lateral travel velocity.

Accordingly, when the rider on the rider mounting section is performingthe turn operation and the lateral travel operation through theoperation unit, the turn velocity command limiting unit sets the turnvelocity command based on the turn operation to a lower value as themanipulated variable of the lateral travel operation increases. Withthis arrangement, the turn velocity command is output within the rangeof the operation limit of the second actuator, prioritizing the lateraltravel of the inverted pendulum type vehicle, thus permitting an easieroperation for the rider to move the inverted pendulum type vehicle inthe lateral direction.

Further, an inverted pendulum type vehicle according to a fourth aspectof the invention includes:

a second travel operation unit, which is connected to the first traveloperation unit or the base body with an interval provided from the firsttravel operation unit in the longitudinal direction and which isconfigured to be capable of traveling in all directions on a floorsurface;

a second actuator which generates a driving force for causing the secondtravel operation unit to travel at least in the lateral direction;

an operation unit which receives, from a rider on the rider mountingsection, a longitudinal travel operation instruction for a travel of theinverted pendulum type vehicle in the longitudinal direction, a lateraltravel operation instruction for a travel of the inverted pendulum typevehicle in the lateral direction, and a turn operation instruction formaking a turn of the inverted pendulum type vehicle;

a velocity command output unit which outputs a longitudinal travelvelocity command for causing the inverted pendulum type vehicle totravel in the longitudinal direction at a command velocity based on amanipulated variable of the longitudinal travel operation, a lateraltravel velocity command for causing the inverted pendulum type vehicleto travel in the lateral direction at a command velocity based on amanipulated variable of the lateral travel operation, and a turnvelocity command for causing the inverted pendulum type vehicle to turnat a command velocity based on a manipulated variable of the turnoperation;

a control processing unit which controls the traveling operations of thefirst travel operation unit and the second travel operation unit byoperating the first actuator and the second actuator according to thelongitudinal travel velocity command, the lateral travel velocitycommand, and the turn velocity command; and

a lateral travel velocity command limiting unit which sets the lateraltravel velocity command to be lower as the manipulated variable of theturn operation increases while the turn operation and the lateral traveloperation are being performed through the operation unit.

In the inverted pendulum type vehicle according to the fourth aspect ofthe invention, the control processing unit may cause the first traveloperation unit and the second travel operation unit to travel at thesame velocity in the lateral direction in order to cause the invertedpendulum type vehicle to travel in the lateral direction. Alternatively,the control processing unit may cause the first travel operation unitand the second travel operation unit to travel at different velocitiesin the lateral direction in order to cause the inverted pendulum typevehicle to turn. Hence, the travel velocity of the second traveloperation unit is determined on the basis of a resultant velocity of thedesired turn velocity and the desired lateral travel velocity.

Accordingly, when the rider on the rider mounting section is performingthe turn operation and the lateral travel operation through theoperation unit, the lateral travel velocity command limiting unit setsthe lateral travel velocity command based on the lateral traveloperation to a lower value as the manipulated variable of the turnoperation increases. With this arrangement, the lateral travel velocitycommand is output within the range of the operation limit of the secondactuator, prioritizing the turn velocity command, thus permitting aneasier operation for the rider to turn the inverted pendulum typevehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating the appearance of an invertedpendulum type vehicle according to an embodiment of the presentinvention;

FIG. 2 is a side view of the inverted pendulum type vehicle according tothe embodiment;

FIG. 3 is a block diagram illustrating the configuration for controllingthe inverted pendulum type vehicle according to the embodiment;

FIG. 4 is a block diagram illustrating the processing by a first controlprocessor shown in FIG. 3;

FIG. 5 is a diagram illustrating an inverted pendulum model used for theprocessing by the first control processor shown in FIG. 3;

FIG. 6 is a block diagram illustrating behaviors related to the invertedpendulum model shown in FIG. 5;

FIG. 7 is a block diagram illustrating the processing an operationcommand converter shown in FIG. 4;

FIG. 8 is a block diagram illustrating the processing by a center ofgravity offset estimator shown in FIG. 4;

FIG. 9 is a block diagram illustrating the processing by a secondcontrol processor shown in FIG. 3;

FIG. 10A is an explanatory chart of the setting map for a longitudinaltravel velocity command based on the movement of a body weight, FIG. 10Bis an explanatory chart of the setting map for the longitudinal travelvelocity command based on the movement of a body weight, and FIG. 10C isan explanatory chart of the setting map for the longitudinal travelvelocity command based on the movement of a body weight;

FIG. 11A is an explanatory chart of the setting map for the longitudinaltravel velocity command based on a joystick, FIG. 11B is an explanatorychart of the setting map for the longitudinal travel velocity commandbased on the joystick, and FIG. 11C is an explanatory chart of thesetting map for the longitudinal travel velocity command based on thejoystick;

FIG. 12A is an explanatory chart of the setting map for a lateral travelvelocity command based on the movement of the body weight, FIG. 12B isan explanatory chart of the setting map for the lateral travel velocitycommand based on the movement of the body weight, and FIG. 12C is anexplanatory chart of the setting map for the lateral travel velocitycommand based on the movement of the body weight;

FIG. 13A is an explanatory chart of the setting map for the lateraltravel velocity command based on a resultant velocity command, FIG. 13Bis an explanatory chart of the setting map for the lateral travelvelocity command based on the resultant velocity command, and FIG. 13Cis an explanatory chart of the setting map for the lateral travelvelocity command based on the resultant velocity command;

FIG. 14A is an explanatory chart of the setting map for the lateraltravel velocity command based on the movement of the body weight, FIG.14B is an explanatory chart of the setting map for the lateral travelvelocity command based on the movement of the body weight, and FIG. 14Cis an explanatory chart of the setting map for the lateral travelvelocity command based on the movement of the body weight;

FIG. 15A is an explanatory chart of the setting map for the lateraltravel velocity command based on the resultant velocity command, FIG.15B is an explanatory chart of the setting map for the lateral travelvelocity command based on the resultant velocity command, and FIG. 15Cis an explanatory chart of the setting map for the lateral travelvelocity command based on the resultant velocity command; and

FIG. 16A is an explanatory chart of the setting map for a turn velocitycommand based on a longitudinal travel velocity, FIG. 16B is anexplanatory chart of the setting map for the turn velocity command basedon the longitudinal travel velocity, and FIG. 16C is an explanatorychart of the setting map for the turn velocity command based on thelongitudinal travel velocity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described with referenceto FIG. 1 to FIG. 16C. As illustrated in FIG. 1 and FIG. 2, an invertedpendulum type vehicle 1 according to the present embodiment (hereinafterreferred to simply as the vehicle 1 in some cases) has a base body 2, afirst travel operation unit 3 and a second travel operation unit 4,which are capable of traveling on a floor surface, and a rider mountingsection 5 on which a rider mounts.

The first travel operation unit 3 includes a circular core member 6shown in FIG. 2 (hereinafter referred to as the annular core member 6)and a plurality of circular rollers 7 mounted on the annular core member6 such that the circular rollers 7 are arranged at equiangular intervalsin the circumferential direction (in the direction about the axialcenter) of the annular core member 6. Each of the rollers 7 isexternally inserted into the annular core member 6 with its rotationalaxial center directed toward the circumference of the annular coremember 6. Further, each of the rollers 7 is configured to be rotatableintegrally with the annular core member 6 about the axial center of theannular core member 6. In addition, each of the rollers 7 is configuredto be rotatable about the central axis of the cross-sectional plane ofthe annular core member 6 (the circumferential axis about the axialcenter of the annular core member 6).

The first travel operation unit 3 having the annular core member 6 andthe plurality of the rollers 7 comes in contact with a floor surfacethrough the intermediary of the rollers 7 (the rollers 7 positioned in alower portion of the annular core member 6), the axial center of theannular core member 6 being directed in parallel to the floor surface.In this ground contact state, the annular core member 6 is rotativelydriven about the axial center thereof so as to cause all the annularcore member 6 and the rollers 7 to circumrotate. This in turn causes thefirst travel operation unit 3 to travel on the floor surface in adirection orthogonal to the axial center of the annular core member 6.In the ground contact state, rotatively driving the rollers 7 abouttheir rotational axial centers causes the first travel operation unit 3to travel in the direction of the axial center of the annular coremember 6.

Further, rotatively driving the annular core member 6 and rotativelydriving the rollers 7 cause the first travel operation unit 3 to travelin a direction at an angle with respect to the direction orthogonal tothe axial center of the annular core member 6 and the direction of theaxial center of the annular core member 6.

Thus, the first travel operation unit 3 is capable of traveling on thefloor surface in all directions. In the following description, of thetraveling directions of the first travel operation unit 3, the directionorthogonal to the axial center of the annular core member 6 is definedas X-axis direction, the direction of the axial center of the annularcore member 6 is defined as Y-axis direction, and a vertical directionis defined as Z-axis direction, as illustrated in FIG. 1 and FIG. 2. Inaddition, a front direction is defined as the positive direction of theX-axis, a left direction is defined as the positive direction of theY-axis, and an upper direction is defined as a positive direction of theZ-axis.

The first travel operation unit 3 is installed to the base body 2. Morespecifically, the base body 2 is provided, covering the first traveloperation unit 3 except for a lower portion thereof in contact with thefloor surface. Further, the base body 2 supports the annular core member6 of the first travel operation unit 3 such that the annular core member6 is rotatable about the axial center thereof. In this case, the basebody 2 uses the axial center of the annular core member 6 of the firsttravel operation unit 3 as the supporting point thereof and the basebody 2 can be tilted about the axial center (about the Y-axis). Further,the base body 2 is tiltable about the X-axis orthogonal to the axialcenter of the annular core member 6 by tilting together with the firsttravel operation unit 3 relative to the floor surface, the groundcontact portion of the first travel operation unit 3 being thesupporting point. Thus, the base body 2 is tiltable about two axesrelative to the vertical direction.

The base body 2 includes therein a first actuator 8, which generates adriving force for moving the first travel operation unit 3, asillustrated in FIG. 2. The first actuator 8 is constituted of anelectric motor 8 a serving as the actuator that rotatively drives theannular core member 6 and an electric motor 8 b serving as the actuatorthat rotatively drives the rollers 7. The electric motors 8 a and 8 bimpart rotative driving forces to the annular core member 6 and therollers 7 through the intermediary of a motive power transmittingmechanisms (not shown). The motive power transmitting mechanisms mayhave publicly known constructions.

The first travel operation unit 3 may have a construction different fromthe aforesaid construction. For example, the first travel operation unit3 and the driving system thereof may adopt the constructions proposed bythe applicant of the present application in PCT WO/2008/132778 or PCTWO/2008/132779.

Further, the rider mounting section 5 is installed to the base body 2.The rider mounting section 5 is formed of a seat, on which a rider sits,and fixed to the upper end portion of the base body 2. A rider can siton the rider mounting section 5, the longitudinal direction thereofbeing the X-axis direction and the lateral direction thereof being theY-axis direction. The rider mounting section 5 (the seat) is secured tothe base body 2, so that the rider mounting section 5 can be tiltedintegrally with the base body 2 relative to the vertical direction.

Further attached to the base body 2 are a pair of footrests 9 and 9, onwhich the rider sitting on the rider mounting section 5 places his/herfeet, and a pair of handles 10 and 10 held by the rider. The footrests 9and 9 are protrusively provided in lower portions of both sides of thebase body 2. In FIG. 1 and FIG. 2, one (the right one) of the footrests9 is not shown.

The handles 10 and 10 are formed of bar-like members disposed extendedlyin the X-axis direction (the longitudinal direction) on both sides ofthe rider mounting section 5 and are respectively fixed to the base body2 through rods 11 extended from the base body 2. Further, a joystick 12serving as an operation device, which constitutes the operating unit inthe present invention, is attached to one handle 10 (the right handle 10in the drawing) of the pair of handles 10 and 10.

The joystick 12 can be swung in the longitudinal direction (the X-axisdirection) and the lateral direction (the Y-axis direction). Thejoystick 12 outputs an operation signal indicative of the amount ofswing in the longitudinal direction (the X-axis direction) as a commandfor moving the vehicle 1 forward or backward. The joystick 12 alsooutputs an operation signal indicative of the amount of swing in thelateral direction (the Y-axis direction) as a command for turning thevehicle 1 to the right (clockwise) or the left (counterclockwise), i.e.,a turn command.

Regarding the amount of swing of the joystick 12 in the longitudinaldirection in the present embodiment, i.e., the amount of rotation aboutthe Y-axis corresponding to the manipulated variable of the longitudinaltravel operation in the present invention, the amount of a forward swingis positive, while the amount of a backward swing is negative. Regardingthe amount of a lateral swing of the joystick 12, i.e., the amount ofrotation about the X-axis corresponding to the manipulated variable ofthe turning operation in the present invention, the amount of a leftwardswing is positive, while the amount of a rightward swing is negative.

The second travel operation unit 4 in the present embodiment is formedof a so-called omniwheel. The omniwheel constituting the second traveloperation unit 4 has a publicly known structure, which includes a pairof coaxial annular core members (not shown) and a plurality ofbarrel-like rollers 13 rotatably and externally inserted in each of theannular core members with the rotational axial centers thereof orientedin the circumferential direction of the annular core member.

In this case, the second travel operation unit 4 is disposed at the rearof the first travel operation unit 3 with the axial centers of the pairof annular core members thereof oriented in the X-axis direction (thelongitudinal direction) and is in contact with a floor surface throughthe rollers 13.

The roller 13 of one of the pair of annular core members and the roller13 of the other thereof are arranged such that the phases thereof areshifted in the peripheral directions of the annular core members. Therollers 13 are further configured such that either the roller 13 of oneof the pair of annular core members or the roller 13 of the otherthereof comes in contact with the floor surface when the pair of annularcore members rotates.

The second travel operation unit 4 constituted of the omniwheel isjoined to the base body 2. More specifically, the second traveloperation unit 4 is provided with a housing 14 that covers an upperportion of the omniwheel (all the pair of annular core members and theplurality of the rollers 13). The pair of annular core members of theomniwheel is rotatably supported by the housing 14 such that the pair ofannular core members is rotatable about the axial centers thereof.Further, an arm 15 extended from the housing 14 to the base body 2 isrotatably supported by the base body 2 such that the arm 15 is swingableabout the axial center of the annular core member 6 of the first traveloperation unit 3. Thus, the second travel operation unit 4 is joined tothe base body 2 through the arm 15.

Further, the second travel operation unit 4 is swingable, relative tothe base body 2, about the axial center of the annular core member 6 ofthe first travel operation unit 3 by the swing of the arm 15. Thisallows the rider mounting section 5 to tilt together with the base body2 about the Y-axis while maintaining both the first travel operationunit 3 and the second travel operation unit 4 to be in contact with theground.

Alternatively, the arm 15 may be rotatably supported by the axial centerportion of the annular core member 6 of the first travel operation unit3, and the second travel operation unit 4 may be joined to the firsttravel operation unit 3 through the arm 15.

The base body 2 is provided with a pair of stoppers 16 and 16 thatrestricts the swing range of the arm 15. Hence, the arm 15 is allowed toswing within the range defined by the stoppers 16 and 16. This restrictsthe swing range of the second travel operation unit 4 about the axialcenter of the annular core member 6 of the first travel operation unit 3and consequently the range of tilt of the base body 2 and the ridermounting section 5 about the X-axis. As a result, the base body 2 andthe rider mounting section 5 are prevented from excessively tiltingtoward the rear side of the rider.

The second travel operation unit 4 may be urged by a spring so as to bepressed against the floor surface.

As described above, the second travel operation unit 4 is capable oftraveling on the floor surface in all directions, including the X-axisdirection and the Y-axis direction, as with the first travel operationunit 3, by rotating one or both of the pair of annular core members andthe rollers 13. More specifically, the rotation of the annular coremembers enables the second travel operation unit 4 to travel in theY-axis direction, i.e., the lateral direction. Further, the rotation ofthe rollers 13 enables the second travel operation unit 4 to travel inthe X-axis direction, i.e., the longitudinal direction.

An electric motor 17 serving as the second actuator, which drives thesecond travel operation unit 4, is attached to the housing 14 of thesecond travel operation unit 4. The electric motor 17 is joined to thepair of annular core members so as to rotatively drive the pair ofannular core members of the second travel operation unit 4.

Thus, according to the present embodiment, the travel of the secondtravel operation unit 4 in the X-axis direction is adapted to passivelyfollow the travel of the first travel operation unit 3 in the X-axisdirection. Further, the travel of the second travel operation unit 4 inthe Y-axis direction is implemented by rotatively driving the pair ofannular core members of the second travel operation unit 4 by theelectric motor 17.

Supplementarily, the second travel operation unit 4 may have the sameconstruction as that of the first travel operation unit 3.

The above has described the mechanical configuration of the vehicle 1according to the present embodiment.

Although not shown in FIG. 1 and FIG. 2, in order to control theoperation of the vehicle 1, i.e., to control the operations of the firsttravel operation unit 3 and the second travel operation unit 4, the basebody 2 of the vehicle 1 in the present embodiment incorporates acontroller 20 constituted of an electronic circuit unit, which includesa CPU, a RAM, a ROM and the like, an acceleration sensor 50 whichdetects the accelerations in the directions of three axes of the basebody 2, an angular velocity sensor 51 (gyro-sensor or the like) whichdetects the angular velocities about the three axes, a rotational speedsensor 52 a (encoder or the like) which detects the rotational speed ofthe electric motor 8 a, a rotational speed sensor 52 b which detects therotational speed of the electric motor 8 b, and a rotational speedsensor 53 which detects the rotational speed of the electric motor 17,as illustrated in FIG. 3.

Further, the controller 20 receives outputs of the joystick 12 anddetection signals of the acceleration sensor 50, the angular velocitysensor 51, the rotational speed sensor 52 a, the rotational speed sensor52 b, and the rotational speed sensor 53.

The controller 20 uses a publicly known method to acquire themeasurement value of the tilt angle of the rider mounting section 5,i.e., the tilt angle of the base body 2, from the detection signals ofthe acceleration sensor 50 and the angular velocity sensor 51. As themethod, the one proposed by the applicant of the present application in,for example, Japanese Patent No. 4181113 may be adopted.

More specifically, the tilt angle of the rider mounting section 5 (orthe tilt angle of the base body 2) in the present embodiment is the tiltangle (a set of a tilt angle in the direction about the X-axis and atilt angle in the direction about the Y-axis), which uses, as itsreference (zero), the posture of the rider mounting section 5 (or thebase body 2) in a state wherein the total center of gravity of thecombination of the vehicle 1 and the rider mounted on the rider mountingsection 5 in a predetermined posture (standard posture) is positionedright above the ground contact portion of the first travel operationunit 3 (upward in the vertical direction).

Based on a detection signal of the angular velocity sensor 51, thecontroller 20 acquires the measurement value of the angular velocity ofthe vehicle 1 about the yaw axis.

To provide a function implemented by an installed program or the like inaddition to the function for acquiring the measurement values asdescribed above, the controller 20 further includes a first controlprocessor 24, which controls the electric motors 8 a and 8 bconstituting the first actuator 8 thereby to control the travelingmotion of the first travel operation unit 3, a second control processor25, which controls the electric motor 17 serving as the second actuatorthereby to control the traveling motion of the second travel operationunit 4, a longitudinal travel velocity command limiter 26, which limitsa velocity command of the travel of the vehicle 1 in the longitudinaldirection, a lateral travel velocity command limiter 27, which limitsthe velocity command of the travel of the vehicle 1 in the lateraldirection, and a turn velocity command limiter 28, which limits a turnvelocity command of the vehicle 1.

The first control processor 24 carries out the arithmetic processing,which will be discussed hereinafter, to sequentially calculate a firstdesired velocity, which is the desired value of the travel velocity(more specifically, the set of a translational velocity in the X-axisdirection and a translational velocity in the Y-axis direction) of thefirst travel operation unit 3. Then, the first control processor 24controls the rotational speed of each of the electric motors 8 a and 8 bthereby to match the actual travel velocity of the first traveloperation unit 3 to the first desired velocity.

In this case, the relationship between the rotational speed of each ofthe electric motors 8 a and 8 b and the actual travel velocity of thefirst travel operation unit 3 is established beforehand. Hence, thedesired value of the rotational speed of each of the electric motors 8 aand 8 b is specified on the basis of the first desired velocity of thefirst travel operation unit 3.

Then, the first control processor 24 feedback-controls the rotationalspeeds of the electric motors 8 a and 8 b to the desired valuesspecified on the basis of the first desired velocity, therebycontrolling the actual travel velocity of the first travel operationunit 3 to the first desired velocity.

Further, the second control processor 25 carries out the arithmeticprocessing, which will be discussed hereinafter, to sequentiallycalculate a second desired velocity, which is the desired value of thetravel velocity (more specifically, the translational velocity in theY-axis direction) of the second travel operation unit 4. Then, thesecond control processor 25 controls the rotational speed of theelectric motor 17 thereby to match the actual travel velocity of thesecond travel operation unit 4 in the Y-axis direction to the seconddesired velocity.

In this case, the relationship between the rotational speed of theelectric motor 17 and the actual travel velocity of the second traveloperation unit 4 in the Y-axis direction is established beforehand, aswith the case of the first travel operation unit 3. Hence, the desiredvalue of the rotational speed of the electric motor 17 is specified onthe basis of the second desired velocity of the second travel operationunit 4.

Then, the second control processor 25 feedback-controls the rotationalspeed of the electric motor 17 to the desired value specified on thebasis of the second desired velocity, thereby controlling the actualtravel velocity of the second travel operation unit 4 in the Y-axisdirection to the second desired velocity.

Supplementarily, according to the present embodiment, the travel of thesecond travel operation unit 4 in the X-axis direction is passivelyimplemented by following the travel of the first travel operation unit 3in the X-axis direction. Hence, there is no need to set the desiredvalue of the travel velocity of the second travel operation unit 4 inthe X-axis direction.

In the explanation of the embodiments in the present description, thevelocity of the first travel operation unit 3 means the moving velocityof the ground contact point of the first travel operation unit 3 unlessotherwise specified. Similarly, the velocity of the second traveloperation unit 4 means the moving velocity of the ground contact pointof the second travel operation unit 4 unless otherwise specified.

The processing by the first control processor 24 and the second controlprocessor 25 will now be described in further detail. First, theprocessing by the first control processor 24 will be described withreference to FIG. 4 to FIG. 8.

As illustrated in FIG. 4, the first control processor 24 has, as majorfunctional units thereof, an operation command converter 31 whichconverts the swing amount of the joystick 12 in the longitudinaldirection (the amount of rotation about the Y-axis) Js_x and the swingamount thereof in the lateral direction (the amount of rotation aboutthe X-axis) Js_y, which are indicated by an operation signal input fromthe joystick 12, into a velocity command for the travel of the vehicle1, a center of gravity desired velocity determiner 32 which determinesthe desired velocity of the total center of gravity of the combinationof the vehicle 1 and the rider on the rider mounting section 5(hereinafter referred to as the vehicle system total center of gravity),a center of gravity velocity estimator 33 which estimates the velocityof the vehicle system total center of gravity, and a posture controlarithmetic unit 34 which determines the desired value of the travelvelocity of the first travel operation unit 3 such that the posture ofthe rider mounting section 5, i.e., the posture of the base body 2, isstabilized while making the estimated velocity of the vehicle systemtotal center of gravity follow a desired velocity. The first controlprocessor 24 carries out the processing by the aforesaid functionalunits at a predetermined arithmetic processing cycle of the controller20.

In the present embodiment, the vehicle system total center of gravityhas a meaning as an example of the representative point of the vehicle1. Accordingly, the velocity of the vehicle system total center ofgravity has a meaning as the translational moving velocity of therepresentative point.

Before specifically describing the processing carried out by each of thefunctional units of the first control processor 24, the basic matters ofthe processing will be described. The dynamic behavior of the vehiclesystem total center of gravity (more specifically, the behavior observedfrom the Y-axis direction and the behavior observed from the X-axisdirection) is approximately expressed by an inverted pendulum modelshown in FIG. 5. The algorithm of the processing by the first controlprocessor 24 is created on the basis of the behavior.

In the following description and FIG. 5, a suffix “_x” means a referencecode of a variable or the like observed from the Y-axis direction, whilea suffix “_y” means a reference code of a variable or the like observedfrom the X-axis direction. Further, in FIG. 5, the reference codes ofthe variables observed from the Y-axis direction are not parenthesized,while the reference codes of the variables observed from the X-axisdirection are parenthesized in order to illustrate both an invertedpendulum model observed from the Y-axis direction and an invertedpendulum model observed from the X-axis direction.

The inverted pendulum model expressing the behavior of the vehiclesystem total center of gravity observed from the Y-axis direction has avirtual wheel 61_x which has a rotational axial center parallel to theY-axis direction and which is circumrotatable on a floor surface(hereinafter referred to as “the virtual wheel 61_x”), a rod 62_x whichis extended from the rotational center of the virtual wheel 61_x andwhich is swingable about the rotational axis of the virtual wheel 61_x(in the direction about the Y-axis direction), and a mass point Ga_xconnected to a reference portion Ps_x, which is the distal end portion(upper end portion) of the rod 62_x.

In the inverted pendulum model, it is assumed that the movement of themass point Ga_x corresponds to the movement of the vehicle system totalcenter of gravity observed from the Y-axis direction, and a tilt angleθb_x (the angle of a tilt in the direction about the Y-axis) of the rod62_x relative to the vertical direction agrees with the angle of a tiltof the rider mounting section 5 (or the base body 2) in the directionabout the Y-axis. Further, the translational movement of the firsttravel operation unit 3 in the X-axis direction corresponds to thetranslational movement in the X-axis direction by the circumrotation ofthe virtual wheel 61_x.

Further, a radius r_x of the virtual wheel 61_x and a height h_x of eachof the reference portion Ps_x and the mass point Ga_x from the floorsurface are set to predetermined values (fixed values) set beforehand.

Similarly, the inverted pendulum model expressing the behavior of thevehicle system total center of gravity observed from the X-axisdirection has a virtual wheel 61_y which has a rotational axial centerparallel to the X-axis direction and which is circumrotatable on thefloor surface (hereinafter referred to as “the virtual wheel 61_y”), arod 62_y which is extended from the rotational center of the virtualwheel 61_y and which is swingable about the rotational axis of thevirtual wheel 61_y (in the direction about the X-axis direction), and amass point Ga_y connected to a reference portion Ps_y, which is thedistal end portion (upper end portion) of the rod 62_y.

In the inverted pendulum model, it is assumed that the movement of themass point Ga_y corresponds to the movement of the vehicle system totalcenter of gravity observed from the X-axis direction, and a tilt angleθb_y (the angle of a tilt in the direction about the X-axis) of the rod62_y relative to the vertical direction agrees with the angle of a tiltof the rider mounting section 5 (or the base body 2) in the directionabout the X-axis. Further, the translational movement of the firsttravel operation unit 3 in the Y-axis direction corresponds to thetranslational movement in the Y-axis direction by the circumrotation ofthe virtual wheel 61_y.

Further, a radius r_y of the virtual wheel 61_y and a height h_y of eachof the reference portion Ps_y and the mass point Ga_y from the floorsurface are set to predetermined values (fixed values) set beforehand.The height h_y of each of the reference portion Ps_y and the mass pointGa_y from the floor surface observed in the X-axis direction is the sameas the height h_x of each of the reference portion Ps_x and the masspoint Ga_x from the floor surface observed in the Y-axis direction.Hereinafter, therefore, h_x=h_y=h will apply.

The positional relationship between the reference portion Ps_x and themass point Ga_x observed from the Y-axis direction will besupplementarily described. The position of the reference portion Ps_xcorresponds to the position of the vehicle system total center ofgravity in the case where it is assumed that the rider mounting(sitting) on the rider mounting section 5 is motionless in apredetermined neutral posture relative to the rider mounting section 5.

In this case, therefore, the position of the mass point Ga_x agrees withthe position of the reference portion Ps_x. The same applies to thepositional relationship between the reference portion Ps_y and the masspoint Ga_y observed from the X-axis direction.

In practice, however, when the rider on the rider mounting section 5moves his/her upper body or the like relative to the rider mountingsection 5 (or the base body 2), the positions of the actual vehiclesystem total center of gravity in the X-axis direction and the Y-axisdirection will usually shift from the positions of the referenceportions Ps_x and Ps_y, respectively, in the horizontal direction. Forthis reason, the positions of the mass points Ga_x and Ga_y, which areshown in FIG. 5, are shifted from the positions of the referenceportions Ps_x and Ps_y, respectively.

The behavior of the vehicle system total center of gravity representedby the inverted pendulum model described above is denoted by thefollowing expressions (1a), (1b), (2a) and (2b). In this case,expressions (1a) and (1b) denote the behaviors observed in the Y-axisdirection, while expressions (2a) and (2b) denote the behaviors observedin the X-axis direction.Vb _(—) x=Vw1_(—) x+h·ωb _(—) x  (1a)dVb _(—) x/dt=(g/h)·(θb _(—) x·(h−r _(—) x)+Ofst_(—) x)+ωz·Vb _(—)y  (1b)Vb _(—) y=Vw1_(—) y+h·ωb _(—) y  (2a)dVb _(—) y/dt=(g/h)·(θb _(—) y·(h−r _(—) y)+Ofst_(—) y)−ωz·Vb _(—)x  (2b)

where Vb_x denotes the velocity of the vehicle system total center ofgravity in the X-axis direction (the translational velocity); θb_xdenotes the tilt angle of the rider mounting section 5 (or the base body2) in the direction about the Y-axis; Vw1_x denotes the moving velocity(the translational velocity) of the virtual wheel 61_x in the X-axisdirection; ωb_x denotes the temporal change rate of θb_x (=dθb_x/dt);Ofst_x denotes the amount of a shift of the position of the vehiclesystem total center of gravity in the X-axis direction (the position ofthe mass point Ga_x in the X-axis direction) from the position of thereference portion Ps_x in the X-axis direction; Vb_y denotes thevelocity of the vehicle system total center of gravity in the Y-axisdirection (the translational velocity); Vw1_y denotes the movingvelocity (the translational velocity) of the virtual wheel 61_y in theY-axis direction; θb_y denotes the tilt angle of the rider mountingsection 5 (or the base body 2) in the direction about the X-axis; andωb_y denotes the temporal change rate of θb_y (=dθb_y/dt); and Ofst_ydenotes the amount of shift of the position of the vehicle system totalcenter of gravity in the Y-axis direction (the position of the masspoint Ga_y in the Y-axis direction) from the position of the referenceportion Ps_y in the Y-axis direction. Further, ωz denotes a yaw rate(the angular velocity in the direction about the yaw axis) when thevehicle 1 turns, and g denotes a gravitational acceleration constant.

The positive direction of θb_x and ωb_x is the direction in which thevehicle system total center of gravity tilts in the positive directionof the X-axis (forward), while the positive direction of θb_y and ωb_yis the direction in which the vehicle system total center of gravitytilts in the positive direction of the Y-axis (leftward). Further, thepositive direction of ωz is the counterclockwise direction as thevehicle 1 is observed from above.

The second term of the right side of expression (1a), namely, (=h·ωb_x),denotes the translational velocity component of the reference portionPs_x in the X-axis direction generated by a tilt of the rider mountingsection 5 in the direction about the Y-axis. The second term of theright side of expression (2a), namely, (=h·ωb_y), denotes thetranslational velocity component of the reference portion Ps_y in theY-axis direction generated by a tilt of the rider mounting section 5 inthe direction about the X-axis.

Supplementarily, Vw1_x in expression (1a) specifically denotes arelative circumferential velocity of the virtual wheel 61_x with respectto the rod 62_x (in other words, with respect to the rider mountingsection 5 or the base body 2). Hence, Vw1_x includes a velocitycomponent (=r_x·ωb_x), which is generated when the rod 62_x tilts, inaddition to the moving velocity of the ground contact point of thevirtual wheel 61_x in the X-axis direction relative to the floorsurface, i.e., the moving velocity of the ground contact point of thefirst travel operation unit 3 in the X-axis direction relative to thefloor surface. The same applies to Vw1_y in expression (1b).

Further, the first term of the right side of expression (1b) denotes anacceleration component in the X-axis direction generated at the vehiclesystem total center of gravity by a component in the X-axis direction(F_x in FIG. 5) of a floor reaction force (F in FIG. 5) acting on theground contact portion of the virtual wheel 61_x according to the amountof shift (=θb_x·(h−r_x)+Ofst_x) of the position of the vehicle systemtotal center of gravity in the X-axis direction (the position of themass point Ga_x in the X-axis direction) from the vertical upperposition of the ground contact portion of the virtual wheel 61_x (theground contact portion of the first travel operation unit 3 observedfrom the Y-axis direction). The second term of the right side ofexpression (1b) denotes the acceleration component in the X-axisdirection generated by a centrifugal force acting on the vehicle 1 atthe time of turning at the yaw rate of ωz.

Similarly, the first term of the right side of expression (2b) denotesan acceleration component in the Y-axis direction generated at thevehicle system total center of gravity by a component in the Y-axisdirection (F_y in FIG. 5) of a floor reaction force (F in FIG. 5) actingon the ground contact portion of the virtual wheel 61_y according to theamount of deviation (=θb_y·(h−r_y)+Ofst_y) of the position of thevehicle system total center of gravity in the Y-axis direction (theposition of the mass point Ga_y in the Y-axis direction) from thevertical upper position of the ground contact portion of the virtualwheel 61_y (the ground contact portion of the first travel operationunit 3 observed from the X-axis direction). The second term of the rightside of expression (2b) denotes the acceleration component in the Y-axisdirection generated by a centrifugal force acting on the vehicle 1 atthe time of turning at the yaw rate of ωz.

The behaviors (the behaviors observed in the X-axis direction)represented by expressions (1a) and (1b) described above are illustratedby the block diagram of FIG. 6. In the diagram, 1/s denotes integrationoperation.

Further, the processing by an arithmetic unit indicated by referencecharacter A in FIG. 6 corresponds to the relational expression ofexpression (1a), while the processing by an arithmetic unit indicated byreference character B corresponds to the relational expression ofexpression (1b).

In FIG. 6, h·θb_x approximately coincides with Diff_x shown in FIG. 5.

Meanwhile, the block diagram representing the behaviors indicated byexpressions (2a) and (2b), i.e., the behaviors observed in the Y-axisdirection, is obtained by replacing the suffix “_x” in FIG. 6 by “_y”and by replacing the sign “+” of the acceleration component (theacceleration component generated by the centrifugal force) at the lowerside in the drawing, which is one of the inputs to an adder denoted byreference character C, by “−.”

According to the present embodiment, the algorithm of the processing bythe first control processor 24 is created on the basis of the behaviormodel (inverted pendulum model) of the vehicle system total center ofgravity that considers the centrifugal force and the amount of the shiftof the vehicle system total center of gravity from the referenceportions Ps_x and Ps_y, as described above.

Based on the above, the processing by the first control processor 24will be specifically described. In the following description, the set ofthe value of a variable related to the behavior observed from the Y-axisdirection and the value of a variable related to the behavior observedfrom the X-axis direction will be denoted by adding a suffix “_xy” insome cases.

Referring to FIG. 4, the first control processor 24 first carries outthe processing by the operation command converter 31 and the processingby the center of gravity velocity estimator 33 at each arithmeticprocessing cycle of the controller 20.

As illustrated in FIG. 7, the operation command converter 31 determinesa basic velocity command Vjs_xy, which is the basic command value of thetravel velocity (the translational velocity) of the first traveloperation unit 3 and a basic turn angular velocity command ωjs, which isthe basic command value of the angular velocity in the direction aboutthe yaw axis when the vehicle 1 turns, on the basis of the amount ofswing of the joystick 12 in the Y-axis direction (i.e., the amount ofrotation about the X-axis) Js_y and the amount of swing of the joystick12 in the X-axis direction (i.e., the amount of rotation about theY-axis) Js_x.

Of the aforesaid basic velocity command Vjs_xy, the basic velocitycommand Vjs_x in the X-axis direction is determined by a processor 31 aon the basis of the amount of swing of the joystick 12 in the X-axisdirection Js_x. More specifically, if the amount of swing Js_x is anamount of swing in the positive direction (an amount of a forwardswing), then the basic velocity command in the X-axis direction Vjs_xwill be a velocity command for a forward movement direction of thevehicle 1 (a positive velocity command). Further, if the amount of swingJs_x is an amount of swing in the negative direction (an amount of abackward swing), then the basic velocity command in the X-axis directionVjs_x will be a velocity command for a backward movement direction ofthe vehicle 1 (a negative velocity command).

In this case, the magnitude of the basic velocity command in the X-axisdirection Vjs_x is determined such that it increases to a predeterminedupper limit value or less as the magnitude of the amount of swing of thejoystick 12 in the X-axis direction (the forward or the backwarddirection) Js_x increases.

A predetermined range in which the magnitude of a swing amount of thejoystick 12 in the positive direction or the negative direction Js_x issufficiently small may be defined as a dead zone, and the basic velocitycommand in the X-axis direction Vjs_x may be set to zero for a swingamount in the dead zone. The graph shown in the processor 31 a in FIG. 7indicates the relationship between an input (Js_x) and an output (Vjs_x)in the case where the dead zone is involved.

Of the basic velocity commands Vjs_xy, the basic velocity command Vjs_yin the Y-axis direction is determined as the velocity command in theY-axis direction of the first travel operation unit 3 for a turn of thevehicle 1 on the basis of the a swing amount of the joystick 12 in theY-axis direction Js_y. More specifically, if the swing amount Js_y is aswing amount in the negative direction (a rightward swing amount), thenthe basic velocity command Vjs_y in the Y-axis direction will be aleftward velocity command (a positive velocity command) of the vehicle1. Further, if the swing amount Js_y is a swing amount in the positivedirection (a leftward swing amount), then the basic velocity commandVjs_y in the Y-axis direction will be the rightward velocity command (anegative velocity command) of the vehicle 1. In this case, the magnitudeof the basic velocity command in the Y-axis direction Vjs_y isdetermined such that it increases to a predetermined upper limit valueor less as the magnitude of the swing amount of the joystick 12 in theY-axis direction (rightward or leftward) increases.

More specifically, as illustrated in, for example, FIG. 7, the basicturn angular velocity command ωjs, which is the basic command value ofthe angular velocity in the direction about the yaw axis when thevehicle 1 turns, is determined on the basis of the swing amount of thejoystick 12 in the Y-axis direction Js_y by the processing carried outby a processor 31 b. In this case, if the swing amount of the joystick12 Js_y is a swing amount in the negative direction (the rightward swingamount), then the basic turn angular velocity command ωjs will be anangular velocity command of a right-hand (clockwise) turn, i.e., anegative angular velocity command. If the swing amount of the joystick12 Js_y is a swing amount in the positive direction (leftward swingamount), then the basic turn angular velocity command ωjs will be anangular velocity command of a left-hand (counterclockwise) turn, i.e., apositive angular velocity command. In this case, the magnitude of thebasic turn angular velocity command ωjs is determined such that itincreases to a predetermined upper limit value or less as the magnitudeof the swing amount of the joystick 12 in the Y-axis directionincreases.

Further, a processor 31 c determines the basic velocity command in theY-axis direction Vjs_y of the first travel operation unit 3 bymultiplying the aforesaid basic turn angular velocity command ωjs by anegative value K, which is (−1) times a predetermined value (>0) setbeforehand as the distance in the X-axis direction between aninstantaneous turn center of the vehicle 1 and the ground contact pointof the first travel operation unit 3.

Hence, the basic velocity command in the Y-axis direction Vjs_y of thefirst travel operation unit 3 is determined such that it is proportionalto the basic turn angular velocity command ωjs, which is determined onthe basis of the swing amount in the Y-axis direction Js_y of thejoystick 12.

Alternatively, however, regarding the magnitude of the basic velocitycommand Vjs_y or the basic turn angular velocity command ωjs, apredetermined range in which the magnitude of a swing amount of thejoystick 12 in the Y-axis direction is sufficiently small may be definedas a dead zone, and the basic velocity command in the Y-axis directionVjs_y or the basic turn angular velocity command ωjs may be set to zeroin the case of a swing amount falling in the dead zone. The graph givenin the processor 31 b in FIG. 7 indicates the relationship betweeninputs (Js_y) and outputs (ωjs) in the case where the dead zone isinvolved.

If the joystick 12 is operated in both the X-axis direction (thelongitudinal direction) and the Y-axis direction (the lateraldirection), then the magnitude of the basic velocity command in theY-axis direction Vjs_y may be set so as to change according to the swingamount of the joystick 12 in the X-axis direction or the basic velocitycommand in the X-axis direction Vjs_x.

In the present embodiment, the state in which the basic turn angularvelocity command ωjs (or the basic velocity command in the Y-axisdirection Vjs_y) determined on the basis of the swing operation of thejoystick 12 in the Y-axis direction (the lateral direction) is not zerocorresponds to a state in which a turn command has been output from thejoystick 12. Further, a state in which ωjs (or Vjs_y) is zerocorresponds to a state in which the turn command has not been outputfrom the joystick 12.

The longitudinal travel velocity command limiter 26 carries out, by theprocessor 31 a, processing for limiting the basic velocity command inthe X-axis direction (the longitudinal direction) Vjs_x, which isdetermined on the basis of the swing amount Js_x (corresponding to themanipulated variable of the longitudinal travel operation in the presentinvention) of the joystick 12. The longitudinal travel velocity commandlimiter 26 changes the basic velocity command Vjs_x in relation to theswing amount Js_x on the basis of the basic turn angular velocitycommand ωjs according to the setting map of the basic velocity commandVjs_x (output) in relation to the swing amount Js_x (input) of thejoystick 12 shown in FIG. 11A to FIG. 11C.

According to the setting map shown in one of FIG. 11A to FIG. 11C, thelongitudinal travel velocity command limiter 26 sets the basic velocitycommand Vjs_x output with respect to the input of the swing amount Js_xof the joystick 12 to be lower as the basic turn angular velocitycommand ωjs increases. For example, in the setting map of FIG. 11C,Vjs_x with respect to the same Js_x is set to become lower at |ωjs2|than at |ωjs1| (<|ωjs2|) throughout the range.

This arrangement allows the vehicle 1 to easily turn by maintaining alow velocity of the vehicle 1 in the longitudinal direction thereby toenable the rider to easily accomplish the turning operation of thevehicle 1 when the basic turn angular velocity command ωjs is high andthe rider is performing an operation for making a quick turn.

The center of gravity velocity estimator 33 calculates an estimatedvalue of the velocity of the vehicle system total center of gravityVb_estm1_xy according to the geometric (dynamic) relationshipexpressions given by the aforesaid expressions (1a) and (2a) in theinverted pendulum model.

More specifically, as illustrated by the block diagram in FIG. 4, thevalue of an actual translational velocity Vw1_act_xy of the first traveloperation unit 3 and the value, which is obtained by multiplying anactual temporal change rate (tilt angular velocity) ωb_act_xy of a tiltangle θb_xy of the rider mounting section 5 by a height h of the vehiclesystem total center of gravity are added up to calculate the estimatedvalue of the velocity of the vehicle system total center of gravityVb_estm1_xy.

More specifically, the estimated value of the velocity in the X-axisdirection Vb_estm1_x of the vehicle system total center of gravity andthe estimated value of the velocity in the Y-axis direction Vb_estm1_ythereof are calculated according to the following expressions (3a) and(3b).Vb_estm1_(—) x=Vw1_act_(—) x+h·ωb_act_(—) x  (3a)Vb_estm1_(—) y=Vw1_act_(—) y+h·ωb_act_(—) y  (3b)

However, the temporal change rate of the offset amount Ofst_xy of theposition of the vehicle system total center of gravity from the positionof the reference portion Ps_xy (hereinafter referred to as the center ofgravity offset amount Ofst_xy) is set to be sufficiently smaller thanVb_estm1_xy so as to be ignorable.

In this case, according to the present embodiment, desired values of thetravel velocity Vw1_cmd_x and Vw1_cmd_y (previous values) of the firsttravel operation unit 3 determined by the posture control arithmeticunit 34 at the previous arithmetic processing cycle are used as thevalues of Vw1_act_x and Vw1_act_y in the above calculation.

Alternatively, however, the rotational speeds of the electric motors 8 aand 8 b, for example, may be detected by the rotational velocity sensors52 a and 52 b, and the latest values of Vw1_act_x and Vw1_act_y (i.e.,the latest values of the measurement values of Vw1_act_x and Vw1_act_y)estimated from the detection values may be used for the calculation ofexpressions (3a) and (3b).

Further, according to the present embodiment, the latest values of thetemporal change rates of the measurement values of the tilt angle θb ofthe rider mounting section 5 based on a detection signal of theacceleration sensor 50 and the angular velocity sensor 51 (i.e., thelatest values of the measurement values of ωb_act_x and ωb_act_y) areused as the values of ωb_act_x and ωb_act_y.

After carrying out the processing by the operation command converter 31and the center of gravity velocity estimator 33 as described above, thefirst control processor 24 carries out the processing by a center ofgravity offset estimator 35 a illustrated in FIG. 4 so as to determine acenter of gravity offset amount estimated value Ofst_estm_xy, which isthe estimated value of the center of gravity offset amount Ofst_xy.

The processing by the center of gravity offset estimator 35 a is theprocessing indicated by the block diagram of FIG. 8. FIG. 8representatively illustrates the processing for determining theestimated value of the center of gravity offset amount in the X-axisdirection Ofst_estm_x of the estimated value of the center of gravityoffset amount Ofst_estm_xy.

The processing in FIG. 8 will be specifically described. The center ofgravity offset estimator 35 a carries out the arithmetic processing ofthe right side of the aforesaid expression (1b) by an arithmetic unit 35a 1 to calculate an estimated value of the translational acceleration ofthe vehicle system total center of gravity in the X-axis directionDVb_estm_x by using the measurement value (a latest value) of an actualtilt angle in the direction about the Y-axis θb_act_x of the ridermounting section 5 obtained from the detection signals of theacceleration sensor 50 and the angular velocity sensor 51, themeasurement value (a latest value) of an actual yaw rate ωz_act of thevehicle 1 obtained from a detection signal of the angular velocitysensor 51, a first estimated value (a latest value) of the velocity ofthe vehicle system total center of gravity in the Y-axis directionVb_estm1_y calculated by the center of gravity velocity estimator 33,and the estimated value of the center of gravity offset amount in theX-axis direction Ofst_estm_x (a previous value) determined at theprevious arithmetic processing cycle.

The center of gravity offset estimator 35 a further carries out theprocessing for integrating the estimated value of the translationalacceleration in the X-axis direction DVb_estm_x of the vehicle systemtotal center of gravity by an arithmetic unit 35 a 2 thereby tocalculate a second estimated value of the velocity of the vehicle systemtotal center of gravity in the X-axis direction Vb_estm2_x.

Subsequently, the center of gravity offset estimator 35 a carries outthe processing for calculating the difference between the secondestimated value of the velocity of the vehicle system total center ofgravity in the X-axis direction Vb_estm2_x (a latest value) and thefirst estimated value Vb_estm1_x (a latest value) thereof by anarithmetic unit 35 a 3.

Then, the center of gravity offset estimator 35 a further carries outthe processing for multiplying the difference by a gain (−Kp) of apredetermined value by an arithmetic unit 35 a 4 so as to determine thelatest value of the estimated value of the center of gravity offsetamount in the X-axis direction Ofst_estm_x.

The processing for determining the estimated value of the center ofgravity offset amount in the Y-axis direction is also carried out in thesame manner described above. More specifically, the block diagramillustrating the determination processing can be obtained by replacingthe suffix “_x” in FIG. 8 by “_y” and by replacing the sign “+” of theacceleration component (an acceleration component generated by acentrifugal force) at right in the drawing, which is one of the inputsto an adder 35 a 5 included in the arithmetic unit 35 a 1, by “−”.

Sequentially updating the estimated value of the center of gravityoffset amount Ofst_estm_xy by the aforesaid processing carried out bythe center of gravity offset estimator 35 a makes it possible toconverge Ofst_estm_xy to an actual value.

The first control processor 24 then carries out the processing by acenter of gravity offset influence amount calculator 35 b shown in FIG.4 to calculate a center of gravity offset influence amount Vofs_xy.

The center of gravity offset influence amount Vofs_xy indicates thedeviation of an actual center of gravity velocity from a desiredvelocity of the vehicle system total center of gravity in the case wherethe feedback control is conducted in the posture control arithmetic unit34, which will be discussed hereinafter, without considering thedeviation of the position of the vehicle system total center of gravityfrom the position of the reference portion Ps_xy in the invertedpendulum mode.

To be specific, the center of gravity offset influence amount calculator35 b multiplies each component of a newly determined estimated value ofthe center of gravity offset amount Ofst_estm_xy by a value denoted by(Kth_xy/(h_r_xy))/Kvb_xy, thereby calculating the center of gravityoffset influence amount Vofs_xy.

Kth_xy denotes a gain value for determining a manipulated variablecomponent which functions to bring the tilt angle of the rider mountingsection 5 close to zero, i.e., to a desired tilt angle, in theprocessing by the posture control arithmetic unit 34, which will behereinafter discussed. Further, Kvb_xy denotes a gain value fordetermining a manipulated variable component which functions to bringthe difference between a desired velocity of the vehicle system totalcenter of gravity Vb_cmd_xy and the first estimated value of thevelocity of the vehicle system total center of gravity Vb_estm1_xy closeto zero in the processing carried out by the posture control arithmeticunit 34, which will be hereinafter discussed.

The first control processor 24 then carries out the processing by thecenter of gravity desired velocity determiner 32 shown in FIG. 4 so asto calculate a restricted center of gravity desired velocity Vb_cmd_xyon the basis of the basic velocity command Vjs_xy determined by theoperation command converter 31 and the center of gravity offsetinfluence amount Vofs_xy determined by the center of gravity offsetinfluence amount calculator 35 b.

The center of gravity desired velocity determiner 32 first carries outthe processing through a processor 32 c shown in FIG. 4. The processor32 c carries out dead-zone processing and limiting related to the valueof the center of gravity offset influence amount Vofs_xy thereby todetermine a desired center of gravity velocity addition amountVb_cmd_by_ofs_xy as a component based on the center of gravity offset ofa desired value of the vehicle system total center of gravity.

More specifically, according to the present embodiment, if the magnitudeof the center of gravity offset influence amount in the X-axis directionVofs_x is a value within a dead zone, which is a predetermined range inthe vicinity of zero, i.e., a value that is relatively close to zero,then the center of gravity desired velocity determiner 32 sets thedesired center of gravity velocity addition amount in the X-axisdirection Vb_cmd_by_ofs_x to zero.

Further, if the magnitude of the center of gravity offset influenceamount in the X-axis direction Vofs_x is a value that deviates from thedead zone, then the center of gravity desired velocity determiner 32determines the desired center of gravity velocity addition amount in theX-axis direction Vb_cmd_by_ofs_x such that the polarity thereof is thesame as Vofs_x and the magnitude thereof increases as the magnitude ofVofs_x increases. However, the value of the desired center of gravityvelocity addition amount Vb_cmd_by_ofs_x is restricted to the range froma predetermined upper limit value (>0) to a predetermined lower limitvalue (≦0).

The processing for determining the desired center of gravity velocityaddition amount in the Y-axis direction Vb_cmd_by_ofs_y is the same asthe processing described above.

The configuration for determining the amount of the center of gravityoffset influence resulting from the shift of the rider's body weight(the manipulated variables of the velocity command operations in thelongitudinal direction and the lateral direction accrued by the shift ofthe rider's body weight) by the center of gravity velocity estimator 33,the center of gravity offset estimator 35 a and the center of gravityoffset influence amount calculator 35 b corresponds to the function ofthe operation unit in the present invention, and the configurationcombined with the joystick 12 constitutes the operation unit in thepresent invention.

The longitudinal travel velocity command limiter 26 carries out, in theprocessor 32 c, the processing for limiting a desired center of gravityvelocity addition amount in the X-axis direction (the longitudinaldirection) Vb_cmd_by_ofs_x, which is determined on the basis of thecenter of gravity offset influence amount Vofs_x (corresponding to thevelocity command based on the shift of the body weight in the X-axisdirection and the manipulated variable of the longitudinal traveloperation in the present invention).

The longitudinal travel velocity command limiter 26 changes the desiredcenter of gravity velocity addition amount Vb_cmd_by_ofs_x with respectto the center of gravity offset influence amount Vofs_x on the basis ofthe basic turn angular velocity command ωjs according to the setting mapof the desired center of gravity velocity addition amountVb_cmd_by_ofs_x (output) with respect to the center of gravity offsetinfluence amount Vofs_x (input) illustrated in FIG. 10A to FIG. 10C.

According to the setting maps in FIG. 10A to FIG. 10C, the longitudinaltravel velocity command limiter 26 sets the desired center of gravityvelocity addition amount Vb_cmd_by_ofs_x output with respect to theinput of the center of gravity offset influence amount Vofs_x to asmaller value as the basic turn angular velocity command ωjs increases.For example, in the setting map of FIG. 10C, Vb_cmd_by_ofs_x withrespect to the same Vost_x is set to become lower at |ωjs2| than at|ωjs1| (<|ωjs2|) throughout the range excluding a dead zone.

This arrangement allows the vehicle 1 to easily turn by maintaining alow velocity of the vehicle 1 in the longitudinal direction thereby toenable the rider to easily accomplish the turning operation of thevehicle 1 when the basic turn angular velocity command ωjs is high andthe rider is performing an operation for making a quick turn.

Further, the lateral travel velocity command limiter 27 carries out, bythe processor 32 c, the processing for limiting the desired center ofgravity velocity addition amount in the Y-axis direction (the lateraldirection) Vb_cmd_by_ofs_y, which is determined on the basis of thecenter of gravity offset influence amount Vofs_y (corresponding to thevelocity command based on the shift of the body weight in the Y-axisdirection and the manipulated variable of the lateral travel operationin the present invention).

The lateral travel velocity command limiter 27 changes the desiredcenter of gravity velocity addition amount Vb_cmd_by_ofs_y with respectto the center of gravity offset influence amount Vofs_y on the basis ofthe basic turn angular velocity command ωjs according to the setting mapof the desired center of gravity velocity addition amountVb_cmd_by_ofs_y (output) with respect to the center of gravity offsetinfluence amount Vofs_y (input) shown in FIG. 12A to FIG. 12C and FIG.14A to FIG. 14C.

FIG. 12A to FIG. 12C apply to the case where the turning direction ofthe vehicle 1 based on the basic turn angular velocity command ωjs andthe direction of the lateral travel based on the center of gravityoffset influence amount Vofs_y are opposite, i.e., the case where ωjs isa rightward angular velocity command (a negative angular velocitycommand) while Vofs_y is a leftward travel command, and the case wherethe ωjs is a leftward angular velocity command (a positive angularvelocity command) while Vofs_y is a rightward travel command.

If the lateral travel velocity command based on Vofs_y is high in thecase where the direction of turning of the vehicle 1 based on the basicturn angular velocity command ωjs and the direction of the lateraltravel based on the center of gravity offset influence amount Vofs_y areopposite, then an undue velocity command for the electric motor 17 ofthe second travel operation unit 4 may result.

Therefore, according to the setting map of one of FIG. 12A to FIG. 12C,the lateral travel velocity command limiter 27 sets the desired centerof gravity velocity addition amount Vb_cmd_by_ofs_y output with respectto the input of the center of gravity offset influence amount Vofs_y toa smaller value as the basic turn angular velocity command ωjsincreases. For example, in the setting map of FIG. 10C, Vb_cmd_by_ofs_ywith respect to the same Vost_y is set to become lower at ωjs2, −ωjs2than at ωjs1, −ωjs1 (|ωjs1<|ωjs2|) throughout the range excluding thedead zone.

This arrangement allows the vehicle 1 to turn within the speed limitrange of the electric motor 17, thereby enabling the rider to easilyaccomplish the turning operation of the vehicle 1.

FIG. 14A to FIG. 14C apply to the case where the turning direction ofthe vehicle 1 based on the basic turn angular velocity command ωjs andthe lateral travel direction based on the center of gravity offsetinfluence amount Vofs_y are the same, i.e., the case where ωjs is arightward angular velocity command (the negative angular velocitycommand) and Vofs_y is a rightward travel command, and the case wherethe ωjs is a leftward angular velocity command (the positive angularvelocity command) and Vofs_y is a leftward travel command.

If the lateral travel velocity command based on Vofs_y is high in thecase where the turning direction of the vehicle 1 based on the basicturn angular velocity command ωjs and the lateral travel direction basedon the center of gravity offset influence amount Vofs_y are the same,then the turn of the vehicle 1 may be hindered.

Therefore, according to the setting map of one of FIG. 14A to FIG. 14C,the lateral travel velocity command limiter 27 sets the desired centerof gravity velocity addition amount Vb_cmd_by_ofs_y output with respectto the center of gravity offset influence amount Vofs_y to a smallervalue as the basic turn angular velocity command ωjs increases. Forexample, in the setting map of FIG. 14C, Vb_cmd_by_ofs_y with respect tothe same Vost_y is set to become lower at ωjs2, −ωjs2 than at ωjs1,−ωjs1 (|ωjs1|<|ωjs2|) throughout the range excluding the dead zone.

This arrangement gives priority to the turning operation of the vehicle1, thus enabling the rider to easily accomplish the turning operation ofthe vehicle 1.

Subsequently, the center of gravity desired velocity determiner 32carries out, by a processor 32 d shown in FIG. 4, the processing fordetermining a desired velocity V1_xy obtained by adding each componentof the desired center of gravity velocity addition amountVb_cmd_by_ofs_xy to each component of the basic velocity command Vjs_xydetermined by the operation command converter 31. More specifically,V1_xy (a set of V1_x and V1_y) is determined by the processing denotedby V1_x=Vjs_x+Vb_cmd_by_ofs_x and V1_y=Vjs_y+Vb_cmd_by_ofs_y.

Further, the center of gravity desired velocity determiner 32 carriesout the processing by a processor 32 e. The processor 32 e carries outlimiting for determining a restricted center of gravity desired velocityVb_cmd_xy (a set of Vb_cmd_x and Vb_cmd_y) as a desired velocity of thevehicle system total center of gravity obtained by restricting thecombination of desired velocities V1_x and V1_y in order to prevent therotational speed of each of the electric motors 8 a and 8 b constitutingthe actuator 8 of the first travel operation unit 3 from deviating froma predetermined permissible range.

In this case, if the set of the desired velocities V1_x and V1_ydetermined by the processor 32 d lies within a predetermined region(e.g., an octagonal region) on a coordinate system, in which the axis ofordinate indicates the value of the desired velocity V1_x and the axisof abscissa indicates the value of the desired velocity V1_y, then thedesired velocity V1_xy is determined directly as the restricted centerof gravity desired velocity Vb_cmd_xy.

Further, if the set of the desired velocities V1_x and V1_y determinedby the processor 32 d deviates from the predetermined region on thecoordinate system, then a set that has been restricted to lie on theboundary of the predetermined region is determined as the restrictedcenter of gravity desired velocity Vb_cmd_xy.

The longitudinal travel velocity command limiter 26 carries out, using aprocessor 32 e, the processing for limiting the restricted center ofgravity desired velocity in the X-axis direction (the longitudinaldirection) Vb_cmd_x (corresponding to specifying the longitudinal travelvelocity in the present invention), the Vb_cmd_x being set on the basisof the desired velocity V1_x (corresponding to the longitudinal traveloperation in the present invention). As with the processor 31 a in FIG.7 described above, according to the same setting maps as the settingmaps shown in FIG. 11A to FIG. 11C (maps in which the desired velocityV1_x is input and the restricted center of gravity desired velocityVb_cmd_x is output), the longitudinal travel velocity command limiter 26sets the restricted center of gravity desired velocity Vb_cmd_x outputwith respect to the input of the desired velocity V1_x to a lower valueas the basic turn angular velocity command ωjs increases

Further, the lateral travel velocity command limiter 27 carries out theprocessing for limiting the restricted center of gravity desiredvelocity in the Y-axis direction (the lateral direction) Vb_cmd_y, whichis determined on the basis of the desired velocity V1_y (correspondingto the manipulated variable of the lateral travel operation in thepresent invention) obtained in the processor 32 e by combining the basicvelocity command Vjs_y and the desired center of gravity velocityaddition amount Vb_cmd_by_ofs_y. The lateral travel velocity commandlimiter 27 changes the restricted center of gravity desired velocityVb_cmd_y relative to the desired velocity V1_y on the basis of the basicturn angular velocity command ωjs according to the setting maps of therestricted center of gravity desired velocity Vb_cmd_y (output) withrespect to the desired velocity V1_y (input) illustrated in FIG. 13A toFIG. 13C and FIG. 15A to FIG. 15C.

FIG. 13A to FIG. 13C apply to the case where the direction of turning ofthe vehicle 1 based on the basic turn angular velocity command ωjs andthe direction of the lateral travel based on the desired velocity V1_yare opposite, i.e., the case where ωjs is a rightward angular velocitycommand (the negative angular velocity command) while V1_y is a leftwardtravel command, and the case where the ωjs is a leftward angularvelocity command (the positive angular velocity command) while V1_y is arightward travel command.

If the lateral travel velocity command based on the desired velocityV1_y is high in the case where the direction of turning of the vehicle 1based on the basic turn angular velocity command ωjs and the directionof the lateral travel based on the desired velocity V1_y are opposite,then an undue velocity command for the electric motor 17 of the secondtravel operation unit 4 may result.

Therefore, according to the setting map of one of FIG. 13A to FIG. 13C,the lateral travel velocity command limiter 27 sets the restrictedcenter of gravity desired velocity Vb_cmd_y output with respect to theinput of the desired velocity V1_y to a smaller value as the basic turnangular velocity command ωjs increases. For example, in the setting mapof FIG. 13C, Vb_cmd_y with respect to the same V1_y is set to becomelower at ωjs2, −ωjs2 than at ωjs1, −ωjs1 (|ωjs1<|ωjs2|) throughout therange excluding the dead zone.

This arrangement allows the vehicle 1 to turn within the speed limitrange of the electric motor 17, thereby enabling the rider to easilyaccomplish the turning operation of the vehicle 1.

FIG. 15A to FIG. 15C apply to the case where the turning direction ofthe vehicle 1 based on the basic turn angular velocity command ωjs andthe direction of the lateral travel based on the desired velocity V1_yare the same, i.e., the case where ωjs is a rightward angular velocitycommand (the negative angular velocity command) and V1_y is a rightwardtravel command, and the case where the ωjs is a leftward angularvelocity command (the positive angular velocity command) and V1_y is aleftward travel command.

If the lateral travel velocity command based on V1_y is high in the casewhere the direction of turning of the vehicle 1 based on the basic turnangular velocity command ωjs and the direction of the lateral travelbased on the desired velocity V1_y are the same, then the turn of thevehicle 1 may be hindered.

Therefore, according to the setting map of one of FIG. 15A to FIG. 15C,the lateral travel velocity command limiter 27 sets the restrictedcenter of gravity desired velocity Vb_cmd_y output with respect to thedesired velocity V1_y to a smaller value as the basic turn angularvelocity command ωjs increases. For example, in the setting map of FIG.15C, Vb_cmd_y with respect to the same V1_y is set to become lower atωjs2, −ωjs2 than at ωjs1, −ωjs1 (|ωjs1|<|ωjs2|) throughout the range.

This arrangement gives priority to the turning operation of the vehicle1, thus enabling the rider to easily accomplish the turning operation ofthe vehicle 1.

The center of gravity desired velocity Vb_cmd_xy is determined on thebasis of the basic velocity command Vjs_xy and the center of gravityoffset influence amount Vofs_xy (or the center of gravity offset) asdescribed above. This enables the rider to maneuver the vehicle 1 byoperating the operation device, i.e., by operating the joystick 12, andby changing the posture of his/her body, i.e., by shifting his/herweight.

After carrying out the processing by the center of gravity desiredvelocity determiner 32, the first control processor 24 carries out theprocessing by the posture control arithmetic unit 34. The posturecontrol arithmetic unit 34 carries out the processing illustrated by theblock diagram of FIG. 4 to determine a first desired velocityVw1_cmd_xy, which is the desired value of the travel velocity(translational velocity) of the first travel operation unit 3.

More specifically, the posture control arithmetic unit 34 first carriesout, by the arithmetic unit 34 b, the processing for subtracting eachcomponent of the center of gravity offset influence amount Vofs_xy fromeach component of the restricted center of gravity desired velocityVb_cmd_xy, thereby determining a desired velocity with a compensatedcenter of gravity offset Vb_cmpn_cmd_xy (a latest value).

Subsequently, according to expressions (4a) and (4b) given below, theposture control arithmetic unit 34 calculates a desired translationalacceleration in the X-axis direction DVw1_cmd_x and a desiredtranslational acceleration in the Y-axis direction DVw1_cmd_y of adesired translational acceleration DVw1_cmd_xy, which is the desiredvalue of the translational acceleration at the ground contact point ofthe first travel operation unit 3, by carrying out the processingthrough the arithmetic units except for the arithmetic unit 34 b and anintegral arithmetic unit 34 a, which carries out integral operations.

$\begin{matrix}{{{DVw1\_ cmd}{\_ x}} = {{{Kvb\_ x} \cdot \left( {{{Vb\_ cmpn}{\_ cmd}{\_ x}} - {{Vb\_ estm1}{\_ x}}} \right)} - {{{Kth\_ x}\; \cdot \;{\theta b\_ act}}{\_ x}} - {{{Kw\_ x} \cdot \;{\omega b\_ act}}{\_ x}}}} & \left( {4a} \right) \\{{{DVw1\_ cmd}{\_ y}} = {{{Kvb\_ y} \cdot \left( {{{Vb\_ cmpn}{\_ cmd}{\_ y}} - {{Vb\_ estm1}{\_ y}}} \right)} - {{{Kth\_ y} \cdot {\theta b\_ act}}{\_ y}} - {{{Kw\_ y}\; \cdot {\omega b\_ act}}{\_ y}}}} & \left( {4b} \right)\end{matrix}$

In expressions (4a) and (4b), Kvb_xy, Kth_xy and Kw_xy denotepredetermined gain values set beforehand.

The first term of the right side of expression (4a) denotes a feedbackmanipulated variable component based on the difference between thecompensated center of gravity-offset desired velocity in the X-axisdirection Vb_cmpn_cmd_x (a latest value) of the vehicle system totalcenter of gravity and a first estimated value Vb_estm1_x (a latestvalue), the second term thereof denotes a feedback manipulated variablecomponent based on a measurement value (a latest value) of an actualtilt angle in the direction about the Y-axis θb_act_x of the ridermounting section 5, and the third term thereof denotes a feedbackmanipulated variable component based on a measurement value (a latestvalue) of an actual tilt angular velocity in the direction about theY-axis ωb_act_x of the rider mounting section 5. Further, a desiredtranslational acceleration in the X-axis direction DVw1_cmd_x iscalculated as a resultant manipulated variable of the above feedbackmanipulated variable components.

Similarly, the first term of the right side of expression (4b) denotes afeedback manipulated variable component based on the difference betweenthe compensated center of gravity-offset desired velocity in the Y-axisdirection Vb_cmpn_cmd_y (a latest value) of the vehicle system totalcenter of gravity and a first estimated value Vb_estm1_y (a latestvalue), the second term thereof denotes a feedback manipulated variablecomponent based on a measurement value (a latest value) of an actualtilt angle in the direction about the X-axis θb_act_y of the ridermounting section 5, and the third term thereof denotes a feedbackmanipulated variable component based on a measurement value (a latestvalue) of an actual tilt angular velocity in the direction about theX-axis ωb_act_y of the rider mounting section 5. Further, a desiredtranslational acceleration in the Y-axis direction DVw1_cmd_y iscalculated as a resultant manipulated variable of the above feedbackmanipulated variable components.

Subsequently, the posture control arithmetic unit 34 integrates thecomponents of the desired translational acceleration DVw1_cmd_xy by theintegral arithmetic unit 34 a, thereby determining a first desiredvelocity Vw1_cmd_xy (a latest value) of the first travel operation unit3.

Then, the first control processor 24 controls the electric motors 8 aand 8 b constituting the actuator 8 of the first travel operation unit 3according to the first desired velocity Vw1_cmd_xy determined asdescribed above. More specifically, the first control processor 24determines the current command values for the electric motors 8 a and 8b by feedback control processing so as to make the actual rotationalvelocities (measurement values) of the electric motors 8 a and 8 bfollow the desired values of the rotational velocities thereof specifiedby the first desired velocity Vw1_cmd_xy. The first control processor 24then energizes the electric motors 8 a and 8 b according to the currentcommand values. Thus, the configuration that controls the operation ofthe electric motors 8 a and 8 b of the first travel operation unit 3according to the first desired velocity Vw1_cmd_xy corresponds to thecontrol processing unit of the present invention.

Due to the processing described above, in a state wherein the restrictedcenter of gravity desired velocity Vb_cmd_xy remains at a fixed valueand the motion of the vehicle 1 has been stabilized after the aforesaidprocessing, i.e., in a state wherein the vehicle 1 is traveling in astraight line at a fixed velocity, the vehicle system total center ofgravity lies right above the ground contact point of the first traveloperation unit 3. In this state, the actual tilt angle θb_act_xy of therider mounting section 5 will be −Ofst_xy/(h−r_xy) according toexpressions (1b) and (2b). The actual tilt angular velocity ωb_act_xy ofthe rider mounting section 5 will be zero and the desired translationalacceleration DVw1_cmd_xy will be zero. This combined with the blockdiagram of FIG. 4 lead to the finding of the agreement betweenVb_estm1_xy and Vb_cmd_xy.

In other words, the first desired velocity Vw1_cmd_xy of the firsttravel operation unit 3 is basically determined to converge thedifference between the restricted center of gravity desired velocityVb_cmd_xy of the vehicle system total center of gravity and the firstestimated value Vb_estm1_xy to zero.

Further, the rotational speeds of the electric motors 8 a and 8 bconstituting the actuator 8 of the first travel operation unit 3 arecontrolled so as not to deviate from a predetermined permissible rangeby the processing carried out by the processor 32 e while compensatingfor the influence on the deviation of the position of the vehicle systemtotal center of gravity from the position of the reference portion Ps_xyin the inverted pendulum model.

This completes the detailed description of the processing by the firstcontrol processor 24 in the present embodiment.

The processing by the second control processor 25 will now be describedwith reference to FIG. 9. To summarize the processing by the secondcontrol processor 25, in a situation wherein the basic turn angularvelocity ωjs determined by the operation command converter 31 is zero(in a situation wherein the swing amount in the Y-axis direction Js_y ofthe joystick 12 is zero or substantially zero), a second desiredvelocity Vw2_cmd_y, which is the desired value of the travel velocity(translational velocity) in the Y-axis direction of the second traveloperation unit 4, is determined to coincide with a first desiredvelocity in the Y-axis direction Vw1_cmd_y of the first travel operationunit 3 in order to cause the vehicle 1 to perform a translationaltravel.

Further, in a situation wherein the basic turn angular velocity ωjs isnot zero, the second control processor 25 determines the second desiredvelocity in the Y-axis direction Vw2_cmd_y of the second traveloperation unit 4 to be different from the first desired velocity in theY-axis direction Vw1_cmd_y of the first travel operation unit 3 in orderto cause the vehicle 1 to turn.

Specifically, the processing by the second control processor 25described above is carried out as follows. Referring to FIG. 9, thesecond control processor 25 first carries out, in a processor 41, theprocessing for limiting the basic turn angular velocity command ωjs bythe turn velocity command limiter 28. The turn velocity command limiter28 sets the limited turn angular velocity command ωjsc with respect tothe basic turn angular velocity command ωjs on the basis of the desiredvalue of the travel velocity in the X-axis direction (the longitudinaldirection) Vw1_cmd_x according to the setting maps of the restrictedturn angular velocity command ωjsc (output) relative to the basic turnangular velocity command ωjs (input) illustrated in FIG. 16A to FIG.16C.

According to the setting map in one of FIG. 16A to FIG. 16C, the turnvelocity command limiter 28 sets the restricted turn angular velocitycommand ωjsc output with respect to the input of the basic turn angularvelocity command ωjs to a lower value as the desired value of the travelvelocity Vw1_cmd_x decreases. FIG. 16A to FIG. 16C illustrate the casewhere the desired value of the travel velocity Vw1_cmd_x is positive(the desired value indicating that the vehicle 1 is traveling forward).For example, in the setting map of FIG. 16C, ωjsc with respect to thesame ωjs is set to become lower at +Vw1_cmd_x1 than at +Vw1_cmd_x2(>+Vw1_cmd_x1) throughout the range.

This arrangement restrains a high-velocity turn angular velocity commandfrom being issued when the desired value of the travel velocityVw1_cmd_x indicating forward travel is low and the rider is trying totravel at a low speed.

Regarding the desired value of the travel velocity in the lateraldirection Vw1_cmd_y, the restricted turn angular velocity command ωjscoutput with respect to the input of the basic turn angular velocitycommand ωjs may be set to a lower value by the turn velocity commandlimiter 28 as Vw1_cmd_y increases (as the manipulated variable of thelateral travel operation increases). This gives priority to the travelof the vehicle 1 in the lateral direction when the restricted turnangular velocity command ωjsc is output within the range of theoperation limit of the electric motor 17, thus enabling the rider toeasily accomplish the operation for moving the vehicle 1 in the lateraldirection.

Subsequently, the second control processor 25 carries out the processingby an arithmetic unit 42. The arithmetic unit 42 determines a basicrelative velocity command Vjs2_y by multiplying the restricted turnangular velocity command ωjsc by a value that is −1 times the distance Lin the X-axis direction (a predetermined value) between the first traveloperation unit 3 and the second travel operation unit 4. The basicrelative velocity command Vjs2_y is a command value of the relativevelocity in the Y-axis direction of the second travel operation unit 4in relation to the first travel operation unit 3 to cause the vehicle 1to turn at the angular velocity of the restricted turn angular velocitycommand ωjsc.

Subsequently, the second control processor 25 carries out, through anarithmetic unit 43, the processing for adding the basic relativevelocity command Vjs2_y (a latest value) to the first desired velocityin the Y-axis direction Vw1_cmd_y (a latest value) of the first traveloperation unit 3 determined by the first control processor 24, therebydetermining the second desired velocity in the Y-axis directionVw2_cmd_y of the second travel operation unit 4.

Then, the second control processor 25 controls the current of theelectric motor 17 serving as the second actuator (consequently thedriving force of the second travel operation unit 4) such that thecurrent actual travel velocity in the Y-axis direction Vw2_act_y of thesecond travel operation unit 4 follows the second desired velocityVw2_cmd_y (a latest value), as illustrated in an arithmetic unit 44 ofFIG. 9.

To be specific, the second control processor 25 determines a currentcommand value Iw2_cmd of the electric motor 17 by carrying out thecalculation of expression (5) given below. The second control processor25 further controls the actual current of the electric motor 17 toIw2_cmd by a motor driver.Iw2_cmd=K2·(Vw2_cmd_(—) y−Vw2_act_(—) y)  (5)

In expression (5), K2 denotes a predetermined gain value set beforehand.

According to the present embodiment, a value estimated from a detectionvalue of the rotational speed of the electric motor 17 (a detectionvalue obtained by a rotational speed sensor, such as a rotary encoder,which is not shown) is used as the value of Vw2_act_y.

The difference between a desired value of the rotational speed of theelectric motor 17 specified by Vw2_cmd_y and the detection value of therotational speed may be used in place of Vw2_cmd_y−Vw2_act_y ofexpression (5).

In the situation wherein the turn command is not being output from thejoystick 12 (the situation in which the basic turn angular velocitycommand ωjs is zero), the second desired velocity Vw2_cmd_y isdetermined such that it agrees with the first desired velocity in theY-axis direction Vw1_cmd_y (a latest value) of the first traveloperation unit 3 by the control processing carried out by the secondcontrol processor 25 described above.

Further, in the situation wherein the turn command is being output fromthe joystick 12 (in the situation wherein the basic turn angularvelocity command ωjs is not zero), the second desired velocity Vw2_cmd_yis determined to be a value obtained by adding the basic relativevelocity command Vjs2_y (a latest value) determined on the basis of thebasic turn angular velocity command ωjs to the first desired velocityVw1_cmd_y in the Y-axis direction (a latest value) of the first traveloperation unit 3. In other words, the second desired velocity Vw2_cmd_yis determined to agree with Vw1_cmd_y+Vjs2_y.

Therefore, the second desired velocity Vw2_cmd_y is determined to take avelocity value that is different from the first desired velocity in theY-axis direction Vw1_cmd_y of the first travel operation unit 3 suchthat the vehicle 1 turns.

More specifically, if the turn command from the joystick 12 is a commandfor turning the vehicle 1 to the right side (in the right-hand turning),i.e., if ωjs is an angular velocity in the clockwise direction, then thebasic relative velocity command Vjs2_y will be a leftward velocity.

At this time, if the first desired velocity in the Y-axis directionVw1_cmd_y of the first travel operation unit 3 is the leftward velocity,then the second desired velocity in the Y-axis direction Vw2_cmd_y ofthe second travel operation unit 4 will be a leftward velocity having amagnitude that is larger than that of Vw1_cmd_y.

In the case where the turn command from the joystick 12 is a command forturning the vehicle 1 to the right (the right-hand direction), if thefirst desired velocity in the Y-axis direction Vw1_cmd_y of the firsttravel operation unit 3 is a rightward velocity, then the second desiredvelocity in the Y-axis direction Vw2_cmd_y of the second traveloperation unit 4 will be a rightward velocity having a magnitude that issmaller than that of Vw1_cmd_y or a velocity in the opposite directionfrom that of Vw1_cmd_y, i.e., the leftward direction.

Meanwhile, if the turn command from the joystick 12 is a command forturning the vehicle 1 to the left (left-hand direction), i.e., if ωjs isan angular velocity in the counterclockwise direction, then the basicrelative velocity command Vjs2_y will be a rightward velocity.

At this time, if the first desired velocity in the Y-axis directionVw1_cmd_y of the first travel operation unit 3 is the rightwardvelocity, then the second desired velocity in the Y-axis directionVw2_cmd_y of the second travel operation unit 4 will be a rightwardvelocity having a magnitude that is larger than that of Vw1_cmd_y.

In the case where the turn command from the joystick 12 is a command forturning the vehicle 1 to the left (the left-hand direction), if thefirst desired velocity in the Y-axis direction Vw1_cmd_y of the firsttravel operation unit 3 is a leftward velocity, then the second desiredvelocity in the Y-axis direction Vw2_cmd_y of the second traveloperation unit 4 will be a leftward velocity having a magnitude that issmaller than that of Vw1_cmd_y or a velocity in the opposite directionfrom that of Vw1_cmd_y, i.e., the rightward direction.

This completes the detailed description of the processing carried out bythe second control processor 25.

The configuration for outputting the basic turn angular velocity commandωjs and the basic velocity command Vjs_xy by the operation commandconverter 31 and the configuration for outputting the desired center ofgravity velocity addition amount Vb_cmd_by_ofs_xy and the restrictedcenter of gravity desired velocity Vb_cmd_xy by the center of gravityoffset estimator 35 a, the center of gravity offset influence amountcalculator 35 b and the center of gravity desired velocity determinerconstitute the velocity command output unit in the present invention.

Further, the configuration in which the first control processor 24controls the energization of the electric motors 8 a and 8 b of thefirst travel operation unit 3 and the second control processor 25controls the energization of the electric motor 17 of the second traveloperation unit 4 corresponds to the control processing unit in thepresent invention.

The vehicle 1 according to the present embodiment described aboveenables the translational travel of the vehicle 1 in the X-axisdirection to be accomplished in response to a longitudinal tilt (in theX-axis direction) of the rider mounting section 5 (or the base body 2)caused by the movement of the body of the rider on the rider mountingsection 5 or in response to the operation of swinging the joystick 12 inthe longitudinal direction.

The translational travel of the vehicle 1 in the Y-axis direction can bealso accomplished in response to a lateral tilt (in the Y-axisdirection) of the rider mounting section 5 (or the base body 2).

Further, combining the aforesaid translational travels enables thevehicle 1 to translationally travel in an arbitrary direction at anangle relative the X-axis direction and the Y-axis direction.

A turn (the change of direction) of the vehicle 1 can be also made tothe right or left side of the vehicle 1 specified by a turn command bysetting the traveling velocities in the Y-axis direction of the firsttravel operation unit 3 and the second travel operation unit 4 todifferent values according to a turn command output in response to theoperation of swinging the joystick 12 in the lateral direction.

Thus, the translational travel and the turn of the vehicle 1 can beeasily made without the need for a complicated operation of an operationdevice, such as the joystick 12, or a complicated motion of the body ofa rider.

When the vehicle 1 is stationary or in other situations wherein thetravel velocity in the Y-axis direction of the first travel operationunit 3 is zero or substantially zero (i.e., when the first desiredvelocity Vw1_cmd_y is zero or substantially zero), if the rider swingsthe joystick 12 in the lateral direction to turn the vehicle 1, then thebasic velocity command Vjs_y, which is the velocity component in theY-axis direction based on the swing amount of the joystick 12 in thelateral direction, will be added to a desired velocity applied in thecase where it is assumed that there has been no operation of swingingthe joystick 12 in the lateral direction, thus providing the desiredvelocity Vb_cmd_xy of the vehicle system total center of gravity, whichis the representative point of the vehicle 1.

If the turn command from the joystick 12 is the command for turning thevehicle 1 to the left (the left-hand direction), then the velocitycomponent Vjs_y will be a rightward velocity. If the turn command fromthe joystick 12 is the command for turning the vehicle 1 to the right(the right-hand direction), then the velocity component Vjs_y will be aleftward velocity.

Basically, therefore, the first desired velocity in the Y-axis directionVw1_cmd_y of the first travel operation unit 3 and the second desiredvelocity in the Y-axis direction Vw2_cmd_y of the second traveloperation unit 4 are set such that they are velocities in the samedirection, while the magnitude of Vw2_cmd_y is greater than that ofVw1_cmd_y.

Thus, the turn (the change of direction) of the vehicle 1 in response tothe operation of swinging the joystick 12 in the lateral direction ismade such that the vehicle 1 rotates in the direction about the yaw axisat each instant during the turn, using an instantaneous turn center in afront region of the ground contact surface of each of the first traveloperation unit 3 and the second travel operation unit 4 as therotational center.

As a result, the rider on the rider mounting section 5 easily senses theturning behavior of the vehicle 1. This enables the rider of the vehicle1 to operate the joystick 12 to obtain a desired turning behavior byproperly recognizing the turning behavior of the vehicle 1.

Further, if, for example, the turn command is output from the joystick12 in the situation wherein the first desired velocity Vw1_cmd_xy of thefirst travel operation unit 3 has been set to zero or substantiallyzero, then a velocity command for turning (≠0) is set as the basicvelocity command in the Y-axis direction Vjs_y related to the firsttravel operation unit 3. This enables the vehicle 1 to turn by movingthe first travel operation unit 3 in the Y-axis direction.

Thus, the frictional force between the first travel operation unit 3 andthe floor surface is reduced, permitting a smooth turn of the vehicle 1.

Further, in the present embodiment, the center of gravity offsetestimator 35 a of the first control processor 24 estimates the center ofgravity offset amount Ofst_xy of the vehicle system total center ofgravity by the processing illustrated in FIG. 8. Hence, the center ofgravity offset amount can be accurately estimated. Then, based on theestimated value Ofst_estm_xy of the center of gravity offset amountOfst_xy, the desired velocity of the vehicle system total center ofgravity (the restricted center of gravity desired velocity) Vb_cmd_xy isdetermined as described above. This allows the center of gravity offsetamount Ofst_xy to properly compensate for the influence exerted on thebehavior of the vehicle 1.

Further, in the vehicle 1 according to the present embodiment, the swingamount (the swing amount in the direction about the Y-axis) of thesecond travel operation unit 4 relative to the base body 2 ismechanically restricted to the predetermined range defined by thestoppers 16 and 16, thereby making it possible to prevent, inparticular, the rider mounting section 5, from excessively leaning tothe rear, which would cause the rider the inconvenience of poorvisibility.

Several modified forms of the aforesaid embodiments will now bedescribed.

In the embodiments described above, the joystick 12 has been used as theoperation device for outputting turn commands and the like; however, atrackball or a touch-pad may be used in place of a joystick.Alternatively, a load sensor adapted to detect a place that comes incontact with a rider or a posture sensor held by a rider may be usedinstead of the joystick.

Further, the second travel operation unit 4 in the aforesaid embodimenthas been the omniwheel formed of a pair of annular core members and aplurality of rollers 13 externally inserted therein. Alternatively,however, the second travel operation unit 4 may be constituted of asingle annular core member and a plurality of rollers externallyinserted therein. The second travel operation unit 4 may furtheralternatively have, for example, the same construction as that of thefirst travel operation unit 3, instead of using the omniwheel.

Further, in the present embodiment, the ground contact point velocityhas been calculated on the basis of the detection signals of theacceleration sensor 50 and the angular velocity sensor 51.Alternatively, however, the ground contact point velocity may bedetected by using other types of sensors.

Further, in the present embodiment, the longitudinal travel velocity hasbeen limited by the longitudinal travel velocity command limiter 26, thelateral travel velocity has been limited by the lateral travel velocitycommand limiter 27, and the turn velocity has been limited by the turnvelocity command limiter 28; however, the advantages of the presentinvention can be obtained by limiting at least one of the longitudinaltravel velocity, the lateral travel velocity and the turn velocity.

What is claimed is:
 1. An inverted pendulum vehicle comprising: a firsttravel operation unit capable of traveling on a floor surface; a firstactuator that drives the first travel operation unit; a base body towhich the first travel operation unit and the first actuator areinstalled; and a rider mounting section attached to the base body suchthat the rider mounting section is tiltable relative to a verticaldirection, wherein the first travel operation unit is configured to becapable of traveling in all directions on the floor surface, including alongitudinal direction and a lateral direction relative to a rider onthe rider mounting section, by a driving force of the first actuator,the inverted pendulum vehicle comprising: a second travel operationunit, which is connected to the first travel operation unit or the basebody with an interval provided from the first travel operation unit inthe longitudinal direction and which is configured to be capable oftraveling in all directions on the floor surface; a second actuatorwhich generates a driving force for causing the second travel operationunit to travel at least in the lateral direction; an operation unitwhich receives, from a rider on the rider mounting section, alongitudinal travel operation instruction for a travel of the invertedpendulum vehicle in the longitudinal direction, a lateral traveloperation instruction for a travel of the inverted pendulum vehicle inthe lateral direction, and a turn operation instruction for making aturn of the inverted pendulum vehicle; a velocity command output unitwhich outputs a longitudinal travel velocity command for causing theinverted pendulum vehicle to travel in the longitudinal direction at acommand velocity based on a manipulated variable of the longitudinaltravel operation, a lateral travel velocity command for causing theinverted pendulum vehicle to travel in the lateral direction at acommand velocity based on a manipulated variable of the lateral traveloperation, and a turn velocity command for causing the inverted pendulumvehicle to turn at a command velocity based on a manipulated variable ofthe turn operation; a control processing unit which controls thetraveling operations of the first travel operation unit and the secondtravel operation unit by operating the first actuator and the secondactuator according to the longitudinal travel velocity command, thelateral travel velocity command, and the turn velocity command; and aturn velocity command limiting unit which sets the turn velocity commandbased on the turn operation to be lower as the manipulated variable ofthe longitudinal travel operation decreases while the turn operation andthe longitudinal travel operation are being performed through theoperation unit.
 2. An inverted pendulum vehicle comprising: a firsttravel operation unit capable of traveling on a floor surface; a firstactuator that drives the first travel operation unit; a base body towhich the first travel operation unit and the first actuator areinstalled; and a rider mounting section attached to the base body suchthat the rider mounting section is tiltable relative to a verticaldirection, wherein the first travel operation unit is configured to becapable of traveling in all directions on the floor surface, including alongitudinal direction and a lateral direction relative to a rider onthe rider mounting section, by a driving force of the first actuator,the inverted pendulum vehicle comprising: a second travel operationunit, which is connected to the first travel operation unit or the basebody with an interval provided from the first travel operation unit inthe longitudinal direction and which is configured to be capable oftraveling in all directions on the floor surface; a second actuatorwhich generates a driving force for causing the second travel operationunit to travel at least in the lateral direction; an operation unitwhich receives, from a rider on the rider mounting section, alongitudinal travel operation instruction for a travel of the invertedpendulum vehicle in the longitudinal direction, a lateral traveloperation instruction for a travel of the inverted pendulum vehicle inthe lateral direction, and a turn operation instruction for making aturn of the inverted pendulum vehicle; a velocity command output unitwhich outputs a longitudinal travel velocity command for causing theinverted pendulum vehicle to travel in the longitudinal direction at acommand velocity based on a manipulated variable of the longitudinaltravel operation, a lateral travel velocity command for causing theinverted pendulum vehicle to travel in the lateral direction at acommand velocity based on a manipulated variable of the lateral traveloperation, and a turn velocity command for causing the inverted pendulumvehicle to turn at a command velocity based on a manipulated variable ofthe turn operation; a control processing unit which controls thetraveling operations of the first travel operation unit and the secondtravel operation unit by operating the first actuator and the secondactuator according to the longitudinal travel velocity command, thelateral travel velocity command, and the turn velocity command; and aturn velocity command limiting unit which sets the turn velocity commandbased on the turn operation to be lower as the manipulated variable ofthe lateral travel operation increases while the turn operation and thelateral travel operation are being performed through the operation unit.3. An inverted pendulum vehicle comprising: a first travel operationunit capable of traveling on a floor surface; a first actuator thatdrives the first travel operation unit; a base body to which the firsttravel operation unit and the first actuator are installed; and a ridermounting section attached to the base body such that the rider mountingsection is tiltable relative to a vertical direction, wherein the firsttravel operation unit is configured to be capable of traveling in alldirections on the floor surface, including a longitudinal direction anda lateral direction relative to a rider on the rider mounting section,by a driving force of the first actuator, the inverted pendulum vehiclecomprising: a second travel operation unit, which is connected to thefirst travel operation unit or the base body with an interval providedfrom the first travel operation unit in the longitudinal direction andwhich is configured to be capable of traveling in all directions on thefloor surface; a second actuator which generates a driving force forcausing the second travel operation unit to travel at least in thelateral direction; an operation unit which receives, from a rider on therider mounting section, a longitudinal travel operation instruction fora travel of the inverted pendulum vehicle in the longitudinal direction,a lateral travel operation instruction for a travel of the invertedpendulum vehicle in the lateral direction, and a turn operationinstruction for making a turn of the inverted pendulum vehicle; avelocity command output unit which outputs a longitudinal travelvelocity command for causing the inverted pendulum vehicle to travel inthe longitudinal direction at a command velocity based on a manipulatedvariable of the longitudinal travel operation, a lateral travel velocitycommand for causing the inverted pendulum vehicle to travel in thelateral direction at a command velocity based on a manipulated variableof the lateral travel operation, and a turn velocity command for causingthe inverted pendulum vehicle to turn at a command velocity based on amanipulated variable of the turn operation; a control processing unitwhich controls the traveling operations of the first travel operationunit and the second travel operation unit by operating the firstactuator and the second actuator according to the longitudinal travelvelocity command, the lateral travel velocity command, and the turnvelocity command; and a lateral travel velocity command limiting unitwhich sets the lateral travel velocity command to be lower as themanipulated variable of the turn operation increases while the turnoperation and the lateral travel operation are being performed throughthe operation unit.